Quantum key distribution (QKD) is a revolutionary cryptography response to the rapidly growing cyberattacks threat posedby quantum computing. Yet, the roadblock limiting the vast expanse of secure quantum communication is the exponentialdecay of the transmitted quantum signal with the distance. Today’s quantum cryptography is trying to solve this problem byfocusing on quantum repeaters. However, efficient and secure quantum repetition at sufficient distances is still far beyondmodern technology. Here, we shift the paradigm and build the long-distance security of the QKD upon the quantum foundationsof the Second Law of Thermodynamics and end-to-end physical oversight over the transmitted optical quantum states. Ourapproach enables us to realize quantum states’ repetition by optical amplifiers keeping states’ wave properties and phasecoherence. The unprecedented secure distance range attainable through our approach opens the door for the development ofscalable quantum-resistant communication networks of the future.